Purification of gas.



H. F. SMITH.

PURIF'CATION 0F GAS APPLICATION FILED OCT. 12 R912.

Patented May 18, 1915.

2 SHEETS-SHEET I LELQQKQSO H. F. SMITH.

- PURiFICATlON OF GAS,

APPLICATION man OCT. 12, 1912.

Patented May 18, 1915.

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HARRY FORD SMITH, OF LEXINGTON, OHIO.

PURIFICATION or ens.

Application filed October 12, 1912. Serial No. 725,444.

To all whom it may concern:

Be it known that I, HARRY F. SMITH, a citizen of the United States,residing at Lexington, in county of Richland and State of Ohio,. haveinvented certain new and use ful Improvements in the Purification ofGas, of which the following is a specification.

This invention relates to an improvement in the purification of gas, andthe object is to pass the gas through a porous diaphragm under'suitablepressure so that the particles, such as tar, will come in contact withthe diaphragm and be caused to coalesce and precipitate. It is theremoval of the small particles of tar vapor or fog that constitrtes theprincipal diiliculty in connection with cleaning gas. These small tarparticles are approximately 1/10,000 of an inch in diam-.

eter and in unclean producer gas there may exist from ten to twentymillions of these small particles per cubic inch. The particles are sosmall that they are carried in suspension in the gas current for anindefinite period and will separate out of the gas with great diflicultyand at extremely slow rates.

Now the objects of the porous diaphragm which constitutes the activeelement of this invention is not to remove the tar from the gas, but tobring about such a combination and agglomeration of the extremely smalltar particles that they will then be too large to be carried forward bythe gas current and will be dropped out and separated from the gas veryreadily by gravitation or by any of the ordinary processes cmpioyed forseparating suspended liquids from gas. This porous diaphragm does notact after the manner of a fiiterbecause a filter entraps and retains theparticies, whereas the object of this diaphragm is to cause thecoalescence of the particles contained or carried by the gas so thatafter the particles coalesce and are increased in size, due to thecoalescence and agglomeration, they Will be carried through the porousdiaphragm by the velocity of the gas passing through the diaphragm, andas the particles have now become heavier than the gas, due to their increased size, they will drop out by gravity and separate themselves fromthe gas.

In the accompanying diawingsFigure 1 discloses an apparatus which may beused in carrying out this invention. although I do Specification ofLetters Patent.

not wish to limit myself to the exact type of apparatus hereindisclosed; Fig. 2 is an enlarged view of one of a series of planes ofthe porous diaphragm Fig. 3 is a diagram or chart showing a quantity ofunseparated material remaining in the gas after it has passed throughthe porous diaphragm under different velocitiesv Referring to Fig. 1of-the drawings, A represents the gas inlet to a gas pump B which pumpcan be of any description that would deliver the gas under pressure,and*C is an outlet or discharge pipe connected to the pump. The gas isdelivered from the pump through the pipe C to a casing 1 and intochamber 2 of the casing. The casing 1 is provided .with two chambers 2and 3 which are separated by a partition 4. A casing 5 is mounted uponthe casing 1 and has communication therewith by ports (3 and 7 formed inthe casings 1 and 5. The gas passes from the chamber 2 of the casing 1into chamber D of the casing 5 and thence through the porous diaphragm Ewhich is mounted in the casing The gas passing through the diaphragmpasses into chamberF on the opposite side of the diaphragmand thencethrough the port 7 into chamber 3 of the casing 1. A separator G isconnected to the casing 1 and is in communication with the chamber 3 ofthe ca sing 1 and from the separator G the gas is discharged through anoutlet opening H.

The gas, before it is admitted to the pump B, is generally cooled,passing through a cooling chamber 8, and from the cooler the gas isadmitted to the pump. In cooling gas containing tar the tar vapors arecondensed in several different forms. A portion of the tar vapor iscondensed directly on the surface of the cooling chamber, but a part iscondensed throughout the volume of the gas in the form of a fine mist ortar fog. It is not, however, essential that the gas should be entirelycold, since good results can be obtained when the gas is fed to theapparatus at temperatures that are considerably .above the ordinaryatmospheric temperature. After the gashas been cooled to causecondensation of the tarry-vapors, it is pumped by the pump B to thechamber D of the casing 5 under the proper pressure so that the gaswillpass' through the diaphragm E. The diaphragm'E is made up of aseries of layers of fibrous or filamentous material such as spun glass,known as glass wool, wool felt, silk, and the like. Sand,

that is, coarse, sand, and metal screens or wiring can be used when madeof propersize but I prefer to use spun glass or glass stituting thescreen. The small dots M represent the size of the tarparticles in the.

gas and their relative distance from one an- .The screen-or diaphragm ismade up of a 7 action of chemical constituents in the gas or other. Theenlarged drawing of course merely represents one plane of the screen.

series of planes. The porous diaphragm is preferably made 3- of an inchthick, al-

though the thickness of" the diaphragm un-' der some conditions willvary. The fibers of this material are sufficiently stiff and elastic toretain their shape under the pressures required and since the glass isentirely indifferent to the action of moisture or chemicals, thestrength and resistance -of the porous diaphragm is not impaired throughthe absorption of moisture or the deleterious tar' handled. I preferablyinclose the glass wool in the form of auniformly distributed sheet orlayer between two fairly coarse Wire screens. In this way the glass issupported at many points so that its shape is not changed by thepressures that are brought to bear upon it. I of course do not Wish tobe limited to this material or to this arrangement or construction, asit is obvious that many forms of apparatus might be em? ployed to embodythis same principle.

From Fig. 2 a very good idea is given of therelative size of thematerial constituting the "porous diaphragm and of the tar pan" ticlesthat are to be removed from thegas and of the spaces between the fibersas they actually lie in the porous diaphragm. Furthermore, the openingsbetween the fibers .are so large that a filtering action in the ordinarysense, cannot occur. words, the tar particles could easily float Inother through the openings without becoming enmeshed in the fibers ofthe diaphragm. This drawing is magnified approximately 600 diameters orthree hundred and sixty thousand times that ofthe actual materials.

phragm together with the high velocity at which the gas passes throughthe minute openings in the diaphragm.

7 As stated before, 'the fiber of the dia:

in thickness and having a sectional area of about one square inch foreach 400 cubic reeaper hour of gas which it is desired to clean. f Thearea of the diaphragm must be small enough that when the gas is flowing,

The result .to be obtained by this invention istherefore dependentiiponthe pervious dia diaphragm. Thegasis much more complctely purified whenpassing through under a difference, of pressure of five pounds than whenpassing through with a difference of pressure of one pound. ,Theprecipitation of the small tar particles is the result of their directcollision with the: fine fibrous material through which the gas isdriven at high velocity. Such collision could; not' occur with any greateffectiveness if the dimensions of the obstructingmaterial were largewith respect to the dimensions of the tar particles. To illustrate mymeaning, it has often been proposed to project smallstreams of gasagainst baffles, diaphragms and the like, whereby a sudden change in-the.direction of the flow of gas'is produced and Lhe tar particles therebycaused. to collide-'8E violently, with the baffles and to be precipitated thereby. Action of this character is imperfect for the reason thatan obstruction of any considerable dimensions would carry ahead of it acushion of compressed gaswhich would tend-to prevent an actual collisonbetween the approaching tar particles and the surface of the baffle."Many of the tar particles w uld 'be shielded 01f; and gradually turnedaside by the action of this gas cushion. Y Now, withthis diaphragm ofthe present invention, the dimensions of the opposing bodies areso smallthat no shielding action. is exerted and the tar particles which moveforward at high velocity are thrown into direct collision with the finethreads and fibers .of the porous diaphragm. The greater the velocitywith which these collisions occur the greater will be the effectivenessof the action, and further the filamentous material or fibers againstwhich the tar particles are rates so as to give ample opportunity forthematerials that are to be separated to become entrapped in the fibersof the filter.-

Now, with this'particular invention, the use of a filter would fail to.give the results,

as it has; been found that when the gas passes through the diaphragm Eat a slow rate, practically no separation of the tar particles from thegas takes place. The separationis only effected when the gas to j becleaned is forced through the porous diacal line at the left give grainsof impurities per cubic foot remaining in the gas. It is accordinglyseen. with below one-half pound pressure the cleaning is veryineflective, and for exceedingly thorough workfrom four to .five poundspressure is required. These as is customary in the centrifugal type oftar facts difl'erenf-iatethis invention from filtering, since infiltering the solid material is completely removed due to slow rates oftravel, and the slower the rates of travel the more effective thecleaning, while with this invention, the higher the velocities themoreeflective the cleaning. This curve or diagram is of course accurate onlyfor the particular conditions that surrounded the test in question, butthey will serve to show the fact that increase in the velocity of gasflow through the diaphragm E results in an increase of the cleanness ofthe gas.

The separator G is an ordinary steam separator such as is used forseparating entrained moisture from steam. In this instance, however, itis intended to cause the final precipitation of all of the particles oftar after they have passed the porous dia phragm E. It is not necessaryto use this apparatus as the tar particles are so heavy that they willdrop out of the gas current.

The practical advantages resulting from this invention are many. Thefirst and most important of these is the fact that by this invention itis possible to secure a inuch greater degree of cleanness in thetreatment of the gas than has been possible to secure heretofore. In,the second place, the apparatus employed is simple in construction anddoes not require rapidly rotating parts such extractor. Furthermore,water is not required except for the purpose of cooling the gas and eventhis is not absolutely essential as the gas can be cooled by aircondensers or other means.

Havingthus described my invention, what I claim asinew and desire tosecure by Letters Patent is;

1. The herein described process of removing tar particles and the likefrom gas which consists in passing the gas through a pervious mediumcausing the particles of -tar to coalesce and the coalesced particles oftar being separated from the pervious medium by the flowing gas.

2. The herein described process of removing tar particles and the likefrom gaswhich consists in passing the gas through a pervious mediumcausing the particles of tar to coalesce and the coalesced particles oftar being separated from the pervious medium lesced particles of tarfrom the gas.

3. The herein described process of removing tar particles and the likefrom gas which consists in passing the gas through a pervious mediumcausing the particles of tar to coalesce and the coalesced particles oftar being separated from the pervious medium by the flowing gas, andseparating the coalesced particles of tar from the gas by gravity.

i. The herein described process of removing tar particles and the likefrom gas which consists in passing the gas through a pervious mediumcausing the particles of tar to coalesce and the coalesced particles oftar being separated from the pervious medium by the flowing gas, andseparating the coalesced particles of tar from the gas by inertia. v

5. The herein described process of rem0ving tar particles and the likefrom gas which consists in obstructing the particles whereby they aremade to coalesce and the coalesced particles being carried beyond theobstruction by the gas. Y

6. The herein described process of removing tar particles and the likefrom gas consisting in passing the gas through a pervious mediumcausingthe tar particles to collide with the pervious medium' andprecipitatethereon producinga coalescence Of the small particles of: tarinto large particles and the large particles being carried through thepervious medium by the gas.

7. The herein described process of remov- I ing tar particles from gaswhich consists in passing the gas through a pervious diaphragm at a highvelocity, and the openings of the diaphragm being sufficiently large topermit the gas and all impurities to pass therethrough, and the tarparticles carried by the gas as it passes through the pervious diaphragmbeing caused to collide with the diaphragm creating a coalescence of thetar particles upon the diaphragm forming large tar particles, whichlarge tar particles are dislodged and carried through the perviousdiaphragm by the gas.

8. The herein described process of removing tar particles from gas whichconsists in passing the 'gas through a pervious diaphragm at a highvelocity, and the openings ingtar. particles-from gas consisting in passing the gasthrough'a. pervious diaphragm at a: high velocity, causingthetar particles tdcollide with the pervious diaphragm and temporarilylodge thereupon during the coalescence and accumulation of the smallparticles upon the diaphragm, and then the accumulated particles aredislodged from the diaphragm by the flowing gas.

10. The herein described process of removin tar articles from asconsistin in b 23 cumulated tar particles are dislodged from thediaphragm by the flowing gas and which particles fall from the gas bygravity.

11. The herein described process of removing tar particles from gaswhich con-- sists in passing the gas through a pervious diaphragm at ahighvelocity, the area of the diaphragm being small enough so thatwhenthe gas passes through the diaphragm there will be a sufficientpressure .3'(-) maintained across the diaphragm for cans-" ing theparticles carried by the gas to collide with the pervious diaphragm andcoalesce thereon and the accumulated particles on the diaphragm beingdislodged therefrom byvthe gas current.

1-2. The herein described process of removing tar partlcles from gaswhich consists passing the gas through-a pervious dias i phragm at a.high velocity; the area ofth to five pounds. maintainedacross thediaphragm for causing the particles carried by the gas to collide with ithe pervious diaphragm and coalesce thereon and the acdiaphragm beingsmallenough so that when the gas passes through the diaphragm there willbe-a difference in pressure of fromone cumulated particles on thediaphragm being dislodged bythe gas current.

13. The herein described process-of removing tar particles from gas,consistingv in cooling the gas for condensing the tar vapors, thenpassing the gas through a pervious medium causing the tar vapors tocollide with the vpervious diaphragm and coalesce thereon, and then thecoalesced tar particles dislodged from the diaphragm by the flowing gas,0 p

.14. The herein-described process of removing tar and the like from gas,which consists'in passing the gas through a per 'vi'ous medium, soconstructed and arranged that under moderate rates of flow, the tarwould not be removed from the gas, but by increasing therate of flow theparticles of far will be separated from the gas and coalesce, and thenseparating the tar particles from the pervious medium.

In testimony whereof I ai -ix my signature in the presence of twoWitnesses- -HARRY FORD SMITH. Witnesses:

ANNA, R. EARHART, WM. H. EARHART.

